Question

a limited region taken on a wavefront which is far away from the source as?

Answer 1

A limited region taken on a wavefront which is far away from the source as?

**Answer:**

A limited region taken on a wavefront which is far away from the source as plane wave.

**Pic.** A wave spreading away from a point source, showing that at large distances a small section of the wavefront looks almost flat.

It is not possible in practice to have a true plane wave; only a plane wave of infinite extent will propagate as a plane wave. However, many waves are approximately plane waves in a localized region of space. For example, a localized source such as an antenna produces a field that is approximately a plane wave far from the antenna in its far-field region.